Mobile-controlled robot

Requirements:

DTMF decoder
3.5mm audio cable (for connecting mobile to DTMF module)
AT89S52
7805
Geared dc motors
Battery (10-12 v)
11.0592MHz crystal
L293D IC (motor driver)
Wheel for motors

Fig. 1: Image showing back side of 8051 Microcontroller based Mobile operated Robot

Image showing top view of 8051 Microcontroller based Mobile operated Robot

Fig. 2: Image showing top view of 8051 Microcontroller based Mobile operated Robot

Image showing front side of 8051 Microcontroller based Mobile operated Robot

Fig. 3: Image showing front side of 8051 Microcontroller based Mobile operated Robot

Image showing side view of 8051 Microcontroller based Mobile operated Robot

Fig. 4: Image showing side view of 8051 Microcontroller based Mobile operated Robot

Description:

Mobile controlling is done mainly with DTMF decoder. DTMF stands for Dual Tone Multi Frequency. This module can take up-to 4 bits of data at a time (i.e. 0-15 decimal values).

DTMF needs two mobile platforms, one for sending instructions while another for receiving them.

This module contains a IC which decodes the signals received and convert it into 4 bit data.

When you press the buttons on the keypad, a connection is made that generates two tones at the same time.

Image showing key mapping of DTMF frequencies for a numeric keypad

Fig. 5: Image showing key mapping of DTMF frequencies for a numeric keypad

generate the tones 1336 Hz and 697 Hz. Sure, the tone 697 is the same for both digits, but it take two tones toWhen you press the digit 1 on the keypad, you generate the tones 1209 Hz and 697 Hz. Pressing the digit 2 will

make a digit and the decoding equipment knows the difference between the 1209 Hz that would complete the digit

1, and a 1336 Hz that completes a digit 2.

This table shows the 4bit data output(bit by bit) from the DTMF decoder module according to the button pressed:

Table listing frequencies and respective digital output used in DTMF

Fig. 6: Table listing frequencies and respective digital output used in DTMF

In this project I have used only 5 keys; they are:

2 (for forward movement)

4 (for moving left) 5 (for stopping the bot) 6 (for moving right)

8 (for backward movement)

A particular DTMF module consists of signal pins (input signals from mobile via 3.5 mm jack), 4 pins (D0, D1, D2, D3,) for transmitting 4 bit data and one DV pin which becomes high on every successful data decoding.

In this project my DTMF 4bit pins are connected to PORT2 of MC (1.e. pin P2^0, 1, 2, 3).

The L293D inputs are connected to pin P1^1,2,3,4 respectively.

L293D will help us to drive DC geared motors perfectly.

In the coding part I have used a user defined header file L293D.h for controlling L293D acoording to the DTMF inputs.

Project Source Code

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Coding (MAIN):

#include
#include
void main()
{
  P2=0xff;
  stop();
  while(1)
 {                            

               if(P2==0xf2)
               {
               forward();
               while(P2==0xf2);
               }
               if(P2==0xf4)
               {
               left();
               while(P2==0xf4);
               }
                if(P2==0xf5)
                {
                stop();
                while(P2==0xf5);
                 }
                if(P2==0xf6)
                {
               right();
               while(P2==0xf6);
                 }
                if(P2==0xf8)
               {
               backward();
               while(P2==0xf8);
                }
}
}





Coding (L293D):

sbit MRp=P1^4;
sbit MRn=P1^3;
sbit MLp=P1^2;
sbit MLn=P1^1;
void forward()
{
   MRp=1; MRn=0;
   MLp=1; MLn=0;
}
void backward()
{
    MRp=0; MRn=1;
    MLp=0; MLn=1;
}
void left()
{
  MRp=1; MRn=0;
  MLp=0; MLn=1;
}
void right()
{
   MRp=0; MRn=1;
   MLp=1; MLn=0;
}
void stop()
{
    MRp=0; MRn=0;
    MLp=0; MLn=0;
}

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